Electrocoating equipment accessory

ABSTRACT

AN ACCESSORY FOR ELECTROCOATING EQUIPMENT CHARACTERIZED BY A FLOATING HELPER ELECTRODE ASSEMBLY MOVABLE WITH RESPECT TO FIXED ELECTRODES DISPOSED ON THE SIDES OF AN ELECTROCOATING TANK, AND WHERE ELECTRICAL ENERGY INDUCED IN SUCH FLOATING HELPER ELECTRODE ASSEMBLY IS PASSED WITHIN A HOLLOW ARTICLE BEING COATED FOR EFFECTIVE INNER COATING ACTION.

y 2, 1972 R. L. KOCH ETAL 3,660,266

ELECTROCOATING EQUIPMENT ACCESSORY F'iled Feb. 12, 1968 26 6 i I "I 35' I 5/ 30 h :1 I N J p A 1 l5 S. I wi y,

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INVENTORS Router 1- !(ocw, 3'

BY Jann- M05114 m/1? United States Patent Office 3,660,266 ELECTROCOATING EQUIPMENT ACCESSORY Robert L. Koch II and James H. Muehlbauer, Evansville, Ind., assignors to Ashdee Corp., Evansville, Ind. Filed Feb. 12, 1968, Ser. No. 704,920 Int. Cl. B01k 5/02; C23b 13/00 U.S. Cl. 204-300 5 Claims ABSTRACT OF THE DISCLOSURE An accessory for electrocoating equipment characterized by a floating helper electrode assembly movable with respect to fixed electrodes disposed on the sides of an electrocoating tank, and where electrical energy induced in such floating helper electrode assembly is passed within a hollow article being coated for effective inner coating action.

As is known, electrocoating, sometimes termed anodic hydrocoating, is a process for applying organic finishes through the use of electrical energy. An improved form of electrocoating apparatus and process is disclosed and claimed in the pending Koch, II et al. United States patent application Ser. No. 440,410, filed Mar. 17, 1965 and entitled Electrocoating.

The electrocoating of articles has proven quite effective and successful; however, some ditficulty has been encountered in the coating of hollow articles. In this connection, in order to achieve full internal coating (a wire connected insertion electrode has oftentimes been employed, providing danger in that such insertion electrode is carried along by the conveyor and does not always travel through the coating area properly. In order to satisfy the internal coating problem, sometimes a bigger paint tank is employed, utilizing higher voltage for added throw-power of the coating material or paint, and, additionally, different types of paint may be used.

The present invention provides an important new approach to the coating of the inside of a hollow article. In this connection, and briefly, a voltage is induced in a floating helper electrode assembly, movable with, but insulated from, the conveyor and the hollow article carried by the conveyor. Two pick-up electrodes and one insertion electrode is employed, the latter being partly positioned within the hollow article, and, due to voltage potential, achieves the desired internal coating. All of the preceding is accomplished without a direct electrical connection, as a wire, thus eliminating the danger problem inherent with the aforesaid internal coating approach employed heretofore.

The size of the overall floating helper electrode assembly is dependent, in part, on the size of the hollow article being coated; the size of the fixed'electrodes along the side walls of the electrocoating tank, and, the chemistry ofthe paint employed. The parameters of distance and voltage are further considerations. As will be evident, the invention is simple in structure and adaptable to various installation techniques.

A better understanding of the invention will become more apparent from the following description, taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a top plan view of an electrocoating arrangement utilizing the invention; and,

FIG. 2 is a view in vertical section of the invention, taken at line 2--2 of FIG. 1 and looking in the direction of the arrows.

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawing and Patented May 2, 1972 specific language will be used to describe the same. It Wlll nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alteratrons and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

With reference to the figures, the invention is described in connection with an electrocoating tank 12 having upstanding side walls 12a, a bottom wall 12b and angling end walls 12c. Spaced inwardly around the side walls 12a of the tank 12 are a series of fixed electrodes 14, where electrically non-conductive members 15 serve as mounting means therefor. A screen 17, defined as a semipermeable membrane for passage of the amine from the paint, might also be utilized. All of the preceding is in accordance with the teachings described and claimed in the aforesaid United States patent application Ser. No. 440,410.

A conventional conveyor 20 is disposed above the tank 12, commonly comprising a I-bean 20a, and a wheelmounted carrier assembly 20b disposed thereon. Any number of such units may be employed, typically being disposed on 18 inch centers.

A support member 22 is mounted on the carrier assembly 2015, where an interconnecting member 23, the central portion 23a of which is electrically non-conductive, further mounts a member 25 for supporting the hollow article 30 to be coated. The latter mounting arrangement might be a crosspiece 26, extending through openings in the hollow article 30, positioned by member 25. It should be understood that the specific structure for mounting the hollow article 30 depends upon the configuration of such article and the overall coating installation.

In any event, another support member 27, typically a rod, extends through the electrically non-conductive portions 23a of the interconnecting member 23, and supports pick-up electrodes 32 at opposite ends thereof. The support member 27 also mounts an insertion electrode 34, where a portion of the latter extends within the hollow article 30 being coated. In one form of the invention, a loose fitting spacer 35 may surround the insertion electrode 34 and position same with respect to the inner surface of the hollow article 30. All of the preceding defines a floating helper electrode assembly.

In use, voltage is applied to the fixed electrodes 14 from a conventional power source (not shown), and induced in the pick-up electrodes 32 forming part of the floating helper electrode assembly. The induced voltage provides a voltage potential within the hollow article 30 by virtue of the insertion electrode 34 disposed therewithin. An important factor is that the voltage drop between the fixed electrodes 14 and the adjacent pick-up electrodes 32 must be below the minimum voltage requirements of the paint to achieve coating. On the other hand, the voltage drop between the insertion electrode 34 inside the hollow article 30 must be greater than the voltage requirements for accomplishing coating.

The various parameters to be considered for any given installationinclude the resistance of the coating material, the size of the article to be coated, the distance between the fixed electrode 14 and the pick-up electrodes 32, and the area of the latter electrodes, termed an interchange area.

As apparent, and importantly, the invention does not require any direct wire connection to an electrical energy source, and provides generally faster coating as well as excellent uniformity in coating. The elimination of any direct wire connection results, as stated above, in a valuable safety feature.

The described electrocoating equipment accessory is susceptible to various changes within the spirit of the invention. For example, the floating helper electrode assembly may be variously reinforced, the configuration and mounting of the insertion electrode changed, or the like. Thus, the above description should be considered illustrative, and not as limiting the scope of the following claims.

We claim:

1. In electrocoating equipment having a tank, a fixed electrode disposed within said tank along a wall thereof, means supplying electrical energy to said fixed electrode, and movable means forming part of a conveyor support ing a hollow article to be coated for movement within said tank, a floating helper electrode assembly comprising at least one pick-up electrode on each movable supporting means, and an insertion electrode on each movable supporting means electrically connected to said at least one pick-up electrode and partly disposed within said hollow article, said at least one pick-up electrode being disposed proximate to said fixed electrode whereby voltage is induced from the latter to effect a voltage potential between said insertion electrode and said hollow article during movement of said hollow article.

2. The structure of claim 1 including means to adjust the voltage between said at least one pick-up electrode and said fixed electrode so as to be less than the minimum voltage required for effecting coating of a coating material.

3. The structure of claim 1 including means to adjust the voltage between said insertion electrode and said hollow article so as to be greater than the minimum voltage required for effecting coating of a coating material.

4. The structure of claim 1 where said movable supporting means, said article and said tank are of one polarity and where said fixed electrode and said helper electrode assembly are of an opposite polarity.

5. The structure of claim 1 where a spacer positions said insertion electrode within said hollow article.

References Cited UNITED STATES PATENTS 3/ 1931 Wurth 204297 8/1959 Metcalfe et al. 204181 US. Cl. X.R. 204299, 181 

